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So as the title says, my intake manifold is cracked. The pictures below should show you what I'm talking about. The port seal appears to be blown out, and it's like this on 3 other cylinders. I can also see a couple other cylinder runners are bulged by the seal walls.
Now, I already bought a new FAST manifold and the supporting modifications to install it, but what would cause this to happen in the first place? The only thing I can think of is maybe I routed my catch can wrong or used elbows in the tubing that were way too restrictive for it. I want to find the root cause before I install the new manifold so this doesn't happen again.
Intake port seal shouldn't be showing lol
Last edited by BryceU_C5; Mar 1, 2023 at 05:11 PM.
Reason: Title revision
Alternatively, do you know the history of the car?
So last time I had the manifold off was roughly June 2021 to replace the oil pressure sensor. I used a torque wrench and torqued to 89in pounds. Prior to that, I bought the car in April of that year from a dealer. I didn't get any records from it.
What's that blue/black striped "loop" thing, in the middle of the picture? Is that the seal that you mentioned being "blown out"? That's on the intake, or "suction" side of the engine, so I doubt that it could be "blown out". Maybe when you reinstalled the intake, a couple of those gaskets popped out of place, before you got it tightened down?
What's that blue/black striped "loop" thing, in the middle of the picture? Is that the seal that you mentioned being "blown out"? That's on the intake, or "suction" side of the engine, so I doubt that it could be "blown out". Maybe when you reinstalled the intake, a couple of those gaskets popped out of place, before you got it tightened down?
So yes, the blue loop thing is my intake seal and I agree that it shouldn't be blown out since it's on the "suction" side of the engine. I suppose the seals could have slipped out of place on install but I find it fairly unlikely. I guess only time will tell when I pull the manifold this weekend.
I've seem to remember a post-somewhere-that a guy cracked an intake because a part of the wiring harness inadvertently got pinched between the head and the intake. IIRC, he tried to draw the gap closed by over tightening the bolts until it snapped/cracked. I may be wrong, but that's what I remember.
I've seem to remember a post-somewhere-that a guy cracked an intake because a part of the wiring harness inadvertently got pinched between the head and the intake. IIRC, he tried to draw the gap closed by over tightening the bolts until it snapped/cracked. I may be wrong, but that's what I remember.
Not saying that it was what happened to the OP, but what you describe certainly would cause the manifold to crack.....along with crushing the wiring harness.
So as the title says, my intake manifold is cracked. The pictures below should show you what I'm talking about. The port seal appears to be blown out, and it's like this on 3 other cylinders. I can also see a couple other cylinder runners are bulged by the seal walls.
Now, I already bought a new FAST manifold and the supporting modifications to install it, but what would cause this to happen in the first place? The only thing I can think of is maybe I routed my catch can wrong or used elbows in the tubing that were way too restrictive for it. I want to find the root cause before I install the new manifold so this doesn't happen again.
Intake port seal shouldn't be showing lol
so here's the manifold and you can see much clearer that the manifold seals blew out somehow and broke the side wall holding them in place on 3 separate cylinder runners. Again I'm really not sure how it happened but here's a better look. I got my new FAST manifold in place and now it's just gone to tie up some loose ends with it.
so here's the manifold and you can see much clearer that the manifold seals blew out somehow and broke the side wall holding them in place on 3 separate cylinder runners. Again I'm really not sure how it happened but here's a better look. I got my new FAST manifold in place and now it's just gone to tie up some loose ends with it.
OP never mentioned that he was using NOS, maybe he's holding out on us.....
I've seen tremendous backfires blow a huge hole in the top of an LS intake. But I've never seen this before. Seems more to me that it was caused by over torqued bolts. Maybe his torque wrench is jacked and he overtightened unknowingly.
He did have the intake off 2 years ago. If it were a design flaw it would have presented itself the 20 years prior to his R&R of the intake.
Looks like there may be a casting problem. The gasket grooves
are not centered.
Has a thick area at the bottom of the gasket seal and very
thin area at the top.
Agree on a backfire could cause the problem.
There are plenty of threads on intake gaskets swelling. You're are obviously very bloated. Did you re-use the originals - if so, they could have been swollen and not seated properly. If you replaced them, what brand were they and have you been using any types of stop leak? A lot of oil gets into the LS1 manifold and the intake seals are exposed to it. These are just questions/observations. Nothing is mentioned if you actually had backfiring, or there are other modifications. I have seen out of position o-rings cause aluminum motorcycle cases to crack when the clamp load is applied. The engine would not have run like this for very long without codes and performance issues - much less the screaming of multiple massive intake leaks.
My Intake manifold cracked. Possible causes??
